Blasting cartridge



Aug.l 18,1931.l F. H. KNEELAND 1,818,995

BLASTING CARTRIDGE Filed Nov. 29. 1929 'MWfQ/ @j 9 @M/966mm @www m4 %L E fq Fatented Aug. i8, 193i UNITED STATESA rara-nr nearer FMR E. XNEELAND, OF CICAGO, ILLINOIS, ASSIGNGR T0 SAFETY MINING COM- PNY, DFGHECAGO, ILLINGIS A COBIPOMTION Bnasrme ernennen Applicatiol lhed November 29, 1929. Serial 30. 410,629.

The present invention is concerned with certain improvements in blasting cartridges of thetype wherein the blastinor medium is a highly compressed or 'liquefied gas and wherein an electrically energizable heater unit is employed to bring about the blasting pressure.

lt isv an object of the invention to simpliy and render more reliable those parts of such a cartridge havingto do with the introduction of the blasting medium and the establishment of the necessary electrical connections for the heater unit.

More particularly, itis an object of the invention to provide separate valve and electrode units,'each of simple and efficientdesign.

Another of the more particular objects of the invention is to provide a 'cartridgeso constructed internally as to automatically and positively guide an inserted heater unit into Contact with' an electrode.

Referring to the drawings,

l'gure l is a view in longitudinal section through aortion of a blasting cartridge embodying t e improvements of the present invention.

Figure 2 is a view in transverse section.

along line 2-2 of Figure l.

Figures 3 and 4 are views inlongitudinal section and end elevation, respectively, of the terminal plug shown in dotted outline in Figure l.,

A blasting cartridge fof the general type with which this invention is concerned is illustrated in the Ferrell etal. Patent No. llSQ/li. rllhis type of cartridge consists of a metallic body having an internal gas chamber, the open end of which is adapted to be closed by a pressure responsive rupturable or other 'suitable form of pressure responsive venting means. rllie opposite end or the cartridge body is provided with an electrode and a charging valve, bothv having communication withthe gas chamben ln order to bring about the desired blasting pressure or thei gaseous charge there is provided an electrically energizalile heater unit,

which entends between and has contact at its opposite ends with the electrode and rupturable disc respectively. In operation, the

heater unit is inserted in the gas chamber and placed in electrical contact with the electrode following which the discharge assembly is applied to the end of the cartridge and so adjusted with respect thereto that the discharge opening is eectively sealed thus conditioned, a'chargeof the blasting medium may be introduced into the chain ber through the adjustable charging valve.

After the cartridge hasbeen thus charged and transported to the place where, it is to be discharged, it is merely necessary to connect the leads from a source .of electricity to the electrode and cartridge body respec-l tively in order to energize the heater and thereby increase the pressure of the charge up to the blasting pressure, at which point the disc or other form of ventingrneans will liberate the charge to do its Worlr,`

The present construction includes a sub- Aagainst the escape of gas. With the cartridge v stantially c lindrical metallic bcd 'l havinga gas cham er 2 of suitable capacity for theo work to be done. Une end of the bod is provided with a discharge opening whic is in communication 'with the interior of the gas chamber and this o ening is designed to be sealed by any suite le form of pressure responsive venting device. This discharge end of the cartridge has not been illustrated herein since it forms no part of the present inentirely separate and independent units.'

This change gives rise to a very advantageous simpliiication ci? both the valve and electrode units and maires possible a far more ecient and reliable electrode and electrode mounting. As shown in the drawings, the electrode 3 is provided `with an intermediate enlarged portion 5 and a reduced portion t which exlll@ - 6 at the ploint Where it tends into` the gas chamber. An insulating sleeve 7 surrounds the portion of the electrode passes through the end wall of t e gas chamber. Interposed between the outer surface of the end wall of the gasthis sleeve there is positioned an electrode ing between nut 11 which has threaded engagement-with the body of the cartridge. The enlar ed portion 5 of the electrode is separated om the electrode nut 11 by means of an insulating disc 12. The electrode nut 11 acts against the outer face kof the enlarged portion 5 of the electrode surface to exert a sealing pressure between the opposite face of the enlarged portion of the electrode and the adjacent surface of the cartridge body through the medium of the disc 8.k It will benoted that portion 6 of the electrode which extends into the gas s chamber is of extremely small cross sectional area as compared withk the type ofelectrode heretofore employed in combination with a valve. It is also to be noted that the enlarged portion 5 of the electrode adords a comparatively large area on which to elfect the sealthe electrode and the body of the cartridge. Thus, owing to the extremely small cross sectional area of that portion of the electrode which is exposed to the pressure within the ga's chamber and the relation of this area to the area of the surface on which the sealing is effected, it is apparent that the extremely high pressures which exist in cartridges of this type at the time of discharge will not seriously affect the condition of the present electrode assembly.

The valve 4 is/-provided with a substantialconical end which extends into a small chamber 15 formed in the body of the car- This chamber is `in communication ing orifice 15 and a passage 14, which has communication with the gas chamber. The valve has threaded connection with the body of the cartridge as indicated at 16 in order that the conical end thereof may be adjusted toward and from tridge. with a char the latter o sealing position with respect to the outer end of the passage 14. A pac ing gland 17 is provided to prevent the escape of gas around the valve unit.

'Another importantv feature of the present construction is the design of' the interior of the gas chamber adjacent the electrode. The end of the gas chamber 2 is formed as indicated at 18 so that the walls thereof converge 1 toward the electrode.

The function of this design is to facilitate the entry of a heater unit and to insure the establishment of contact between an end of the unit and the inner end ofthe electrode. According to current practice, these heater units consist of an elonlgatedpaper tube having metallic end closures which are connected to the leads of an electric matchhead disposed within the tube.

secured in position. -VThe heater unit will automatically become centered and establish contact with the electrode by virtue of the n conical formation of the interior of the gas chamber.

The valve andelectrode unitsk may be pro- 19 having threaded engagetected by a cap mentwith the end of the cartridge body.

This cap is preferably provided with acentral opening 20 for the reception of a terminal plug and one or more openings 21 in which an electric conductor may be secured.

s The terminal plug 22 may be of any suitable form capable of being passed through the opening 20 of the cap and engaging and forming electrical connection with the outer end of the electrode. As herein shown, the plug consists of a metallic body 23, one end of which isformed with a plurality of resilient contact fingers 24. The body is surrounded by an insulating sleeve 25 to prevent contact thereof with the metallic protector cap and the plug assembly is completed by a cap member 26 surrounding the outer end of the insulating body 25. The outer end of the body 23 may be belled out as indicatedl at 27 to secure the several parts of the plug in assembled relation.

I claim:

l. In a blasting cartridge of the type coml prising a substantially cylindrical metallic body having an internal fluid chamber with a discharge opening in one end thereof, the combination of an insulated electrode positioned in the opposite end of said body and extending into said chamber, and an inclined approach to said electrode, whereby a heater unit inserted in said fluid chamber may be automatically guided into position to establish contact with said electrode.

2. In a blasting cartridge ,of the type comprising a substantially cylindrical metallic body having an internal fluid chamber with a discharge o ening in one end thereof, the opposite end fl said bodyhaving a bore of relatively small diameterI communicating with the interior of said fluid chamber and a pocket of relatively large diameter outwardly I of and substantially concentric with said bore,

relatively large diameter adapted to be positioned within said pocket, means for insulating said electrode from said body, and a nut having threaded engagement with said pocket for exerting pressure on said electrode. v

, Signed at Chicago, Illinois, this 19th day of November, 1929.

FRANK H. TKNEELAND. 

